Cardiac electrophysiological activity analysis is used for the management of cardiac disorders and irregularities, such as ventricular myocardial ischemia caused by a lack of blood and oxygen, in heart tissue. Usually, skin surface ECG signal analysis based on waveform time domain parameters is utilized for cardiac arrhythmia detection and characterization, including heart rate variability (HRV), cardiac wave morphology, R wave-ST segment and T wave amplitude analysis. However known cardiac status detection and characterization systems fail to determine severity and quantitatively characterize ongoing ischemia events and are subjective and need extensive clinical expertise and knowledge for accurate use. Inaccurate and subjective evaluation and diagnosis may cause unexpected delay in cardiac rhythm management, drug delivery and emergency treatment.
A 12-lead electrocardiogram (ECG) and multi-channel intra-cardiac electrograms (ICEG) are used for evaluating cardiac rhythm and events. Known waveform morphology parameter analysis systems, such as P wave, QRS complex, ST segment, T wave analysis systems, are used for cardiac arrhythmia monitoring and identification, e.g., of atrial fibrillation (AF), myocardial ischemia (MI) and ventricular tachycardia/fibrillation (VT/VF). However, known waveform morphology parameter analysis is often subjective and time-consuming, and requires extensive medical expertise and clinical experience for accurate interpretation and proper cardiac rhythm management. Additionally, cardiac electrophysiological activity and signals (ECG and ICEG) are time varying and known signal analysis typically cannot localize a precise malfunction and severity of cardiac events (e.g., myocardial ischemia and infarction), and different stages of cardiac pathology irregularity and arrhythmia.
Known clinical methods use electrophysiological (EP) surface ECG and ICEG signal voltage amplitude analysis for arrhythmia detection to identify and characterize cardiac abnormality and arrhythmia related information (such as timing, energy). Known clinical diagnosis standards may be of limited value in some cases. For example, myocardial ischemia and infarction detection is usually based on ST segment voltage deviation for ischemia event detection (e.g. 0.1 mV elevation). However this only works for surface ECG signals not for intra-cardiac electrograms (ICEG signals). Known methods for cardiac arrhythmia analysis, such as myocardial ischemia event detection and evaluation, rely on a repolarization signal portion, such as ST segment and T wave morphology changes. Known methods lack capability for quantitative characterization of cardiac arrhythmia severity and may cause a false alarm. For example amplitude voltage ST segment measurement fails to provide a reliable severity level of an ischemia event. Heart rate variability is unable to provide an arrhythmia urgency level. A system according to invention principles addresses these deficiencies and related problems and provides an earlier more accurate detection and characterization of a cardiac arrhythmia event and can be used in an ICD (intra-cardiac device), for example.